Conventional radio communication methods and radio communication devices when performing ad hoc communication include those disclosed in JP-A-2003-229869. FIG. 22 shows a radio communication method described in JP-A-2003-229869.
In FIG. 22, a radio communication device sets a management information notification cycle at a predetermined time interval and transmits management information in which reception timing information indicating a start position for the radio communication device to receive information, reception window information and reception cycle information are written. Another radio communication device which could receive the management information stores the reception timing, the reception window and the reception cycle by associating them with a communication device number of the radio communication device in question. When transmitting information, the reception start position in the communication device in question is found from the reception timing, the reception window and the reception cycle of the correspondent node, and information is sent according to that timing.
As another conventional example, there is a radio communication device disclosed in JP-A-2004-128616. FIG. 21 is a block diagram showing a configuration of the radio communication device disclosed in JP-A-2004-128616.
In FIG. 21, the conventional radio communication device is provided with a narrowband radio device 2002 and an antenna 2001 which use an ad hoc network system, in addition to a pulse radio device 2004 and an antenna 2003 for pulse communication, and performs transmission and reception of control data such as a request between radio communication terminals by using the narrowband radio device 2002. In this manner, the conventional radio communication device updates schedule information for data communication and performs data communication using a pulse communication format in accordance with that schedule information.
However, in the conventional method disclosed in JP-A-2003-229869, the radio communication device can wait for data frames only during the time the reception window is open, thereby allowing low power consumption, but the reception window receiving transmission requests is designated, so that there is a problem that transmission requests from plural radio communication devices concentrate in the reception window and the possibility that the device can not correctly receive the transmission request may increase.
Since communication requests or communication responses which are not addressed to the device miss the reception window of the device, the device can not receive them. Therefore, there is a problem that the device cannot know time slots of the expanded reception windows in which other radio communication devices receive data. As a result, the possibility that the device transmits data in such time slots increases.
In the conventional radio communication device disclosed in JP-A-2004-128616, the narrowband radio device goes into a waiting mode depending on whether there is a radio communication device or not in the neighboring area, but the pulse radio device is always operating. Therefore, it is difficult to reduce power consumption of the conventional radio communication.